1. Field of the Invention
The present application relates generally to an adjustable support apparatus including an adjustable lift carriage and support member, and more particularly to an adjustable scaffolding structure including an adjustable lift carriage and platform support and a support tower for use therewith.
2. Description of the Prior Art
Various types of adjustable scaffolding exist in the art. Such adjustable scaffolding commonly is used in the construction industry for supporting construction workers and/or materials during the construction, maintenance or demolition of a structure. A common scaffolding structure currently existing in the art includes a cable and winch assembly for raising and lowering a carriage and associated platform support along a plurality of generally vertical tower supports. Although the cable and winch systems have performed generally satisfactorily, cables require a great deal of care and maintenance to maintain their strength. The failure to properly care and maintain cables and the winch assembly in such a system has resulted in system failure and personal injury.
Various types of adjustable scaffolding and lift systems exist in the art. These function primarily to support worker and/or material platforms for use during construction, repair, maintenance or demolition of a structure. Examples include non-cable systems such as those described in the Maack U.S. Pat. No. 3,946,836. Maack discloses the use of a rotatable endless belt with a plurality of regularly spaced openings that sequentially engage lugs protruding from a vertical structure. The belt is supported by two vertically spaced sprockets in which one or more teeth are purposely deleted so that the sprocket teeth do not make contact with the lugs while the sprockets are rotating. A requirement of the Maack disclosure is that the spacing of the lugs must be an integral multiple of the spacing between the belt openings.
The Pujol U.S. Pat. No. 4,534,446, the Patnode U.S. Pat. No. 5,487,446, the Schernekau U.S. Pat. No. 2,007,480, the Knechtel U.S. Pat. No. 1,442,075, the Beck U.S. Pat. No. 3,071,205 and the Allen UK Patent No. 150,011 also disclose non-cable means for moving a platform up and down a vertical structure. The Pujol patent discloses the use of a wheel with radial projections that sequentially engage perforations in the vertical structure and in which the wheels are rotated by a rotatable worm drive and crown gear assembly. The Patnode patent discloses the use of a sprocket with peripheral teeth that sequentially engage apertures in the vertical structure in order to move the attached platform up and down the structure. In Patnode, with the sprocket is rotated by means of a bevel gear assembly. The Schernekeau and Knechtel patents disclose the use of two sets of staggered radial pins which sequentially engage perforations in their respective vertical structures. The Beck and Allen patents disclose using conventional rack and pinion means.
One of the most commonly used adjustable scaffolding systems involves the use of a winch and cable for raising and lowering a support platform relative to a pair of support towers. In these systems one end of the cable is hooked to the top or an upper portion of the tower and the other end is wound onto a winch which is mounted to the carriage. Rotation of the winch causes the carriage and its related structure to be pulled up the tower by the cable. While winch and cable systems function generally satisfactorily, such systems have several limitations. First, cables require a great deal of care and maintenance to maintain their strength. Second, the lift capacity of a winch and cable system is related directly to the size and strength of the cable. For most applications this has practical limitations. Third, use of winch and cable systems is labor intensive in that it requires extensive time for handling and maintaining the cable and dealing with broken, rusted, frayed or otherwise damaged cable. Fourth, when utilizing cable and winch systems, it is necessary to align and re-hook the cable as additional tower sections are added or removed.
Accordingly, there is a need in the art for a lift system, and particularly an adjustable scaffolding system, which improves lift capacity, minimizes care and maintenance, and totally eliminates the cable and winch and the various limitations thereof.